Lubricant composition for the hot pressing of metals and a method for the preparation thereof

ABSTRACT

A LUBRICANT COMPOSITION FOR USE IN THE HOT PRESSING OF METALS WHICH COMPRISES THE FOLLOWING COMPONENTS TAKEN IN WEIGHT PERCENT: VERMINCULITE 60-38 GRAPHITE 0-16 MINERAL OIL 33-23 WOOD SAW-DUST 3-11 SODIUM CHLORIDE 4-12 A METHOD FOR THE PREPARATION OF SAID LUBRICANT COMPOSITION, CHARACTERIZED IN THAT VERMICULITE FREE OF MECHANICAL IMPURITIES IS HEATED UP TO A TEMPERATURE OF ABOUT 900-1100*C. WHICH IS SUBSEQUENTLY GROUND AND MIXED WITH GRAPHITE, WOOD SAW-DUST, SODIUM CHLORIDE AND A MINERAL OIL IN THE TEMPERATURE RANGE FROM ABOUT 60* C. TO ABOUT 80* C. TO OBTAIN A FINAL PRODUCT. THIS LUBRICANT COMPOSITION IS SUITABLE FOR THE PRESSING OF METAL TUBES AND PROFILES.

United States Patent US. Cl. 252-1 Claims ABSTRACT THE DISCLOSURE .A lubricant composition for use in the hot pressing of metals which comprisesthe following components taken in weight percent:

vermiculite 60-38 Graphite 0-16 Mineral oil 33-23 Wood saw-dust 3-11 Sodium chloride 4-12 A method for the preparation of said lubricant composition, characterized in that vermiculite free of mechanical impurities is heated up to a temperature of about 9001l00 C. which is subsequently ground and mixed with graphite, wood saw-dust, sodium chloride and a mineral oil in the temperature range from about 60 C. to about 80C. to obtain a final product.

This lubricant composition is suitable for the pressing of metal tubes and profiles.

The present invention relates to a novel lubricant composition for use in the hot pressing of metals and to a method for the preparation thereof, which lubricant composition is suitable for the pressing of metal tubes and profiles.

Known in the art are lubricant compositions for the hot pressing of metals which comprise graphite, wood flour or saw-dust, high-molecular organic substances such as'polystyr'ene, various oils (animal, vegetable, mineral, synthetic), and salts or metal hydroxides. For instance, there is a lubricant composition for the hot pressing of metals which consists of the following components taken in Weight percent: graphite-60-70; wood saw-dust-5- soot-20-25; pyrolusite'-2-5; dextrine or water glass as a binder. Thereis also known a lubricant composition for use in the hot pressing of metals which comprises 450 weight parts of graphite, 40 weight parts of wood flour, 60 weight parts of pyrolusite, 115 weight parts of polystyrene, 450 weight parts of graphite dust, 1350 weight parts of ethylene trichloride, and 45 weight percent of water glass (S. Y. Veiler, V. I. Likhtman, The Action of Lubricant Compositions in the Pressing of Metals published by the Academy of Sciences of the U.S.S.R., 1960; British Pat. No. 790,398; French Pat. No. 1,191,503).

The significant disadvantage of all the known graphitecontaining lubricant compositions is in their ability to carbonize the surfaces of pressed articles which exerts an adverse effect on the plastic properties and the quality of produced articles.

Therefore, the articles pressed with the use of graphitecontaining lubricants, particularly the articles intended for the cold rolling or drawing, are subjected to a special thermal treatment for decarbonization. This method is not always effective and does not yield positive results in the production of ribbed boiled tubes.

An object of the present invention is to develop a lubricant composition of improved quality which is capable of reducing the surface carbonization of pressed articles, and eliminating the special thermal treatment necessary for decarbonizing such articles and thereby providing a considerable economic effect.

This object is achieved by providing a lubricant composition for the hot pressing of metals consisting of graphite, mineral oil, wood saw-dust and sodium chloride, which composition, according to the present invention, comprises also vermiculite.

According to this invention, the advanced lubricant composition consists of the following components taken in weight percent; vermiculite-60-38; graphite-046; mineral oil-33-23; wood saw-dust-S-ll; sodium chloride-4-12.

The most preferable lubricant compositions are the following (taken in weight percent): vermiculite56; flaky graphite-0; mineral oil29; wood saw-dust--8; sodium chloride-7; or vermiculite-40; flaky graphite 16; mineral oil--27; wood saw-dust9; sodium chloride-8.

The method for the preparation of the lubricant composition, according to the present invention, is characterized in that vermiculite free of mechanical impurities is heated up to 900-1100" C. and is subsequently ground and mixed with graphite, wood saw-dust, sodium chloride, and mineral oil in the temperature range from about 60 C. to about C. to obtain a final product.

It is advisable to grind vermiculite up to a particle size less than 0.6-1 mm.

The amount of graphite in the lubricant composition, according to the present invention, is completely or mostly substituted by vermiculate. This makes it possible to reduce the amount of carbon-containing components in the lubricant composition and, due to the ability of vermiculite to envelop graphite particles, to limit the contact of the latter with the metal being deformed.

The flaky texture, low hardness, high melting temperature, low heat-conductivity, and chemical inertness of vermiculite are valuable properties in the use of vermiculite as the base of a technological lubricant composition. In addition to the elimination of the carbonizing characteristics of a lubricant, this makes it possible to keep its high technological elfectiveness and provide high quality produced articles.

Prior to the preparation of the lubricant composition, the natural vermiculite is heated up to a temperature from about 900 C. to about 1100" C. and ground up to a particle size less than 0.6-1 mm. Any mechanical impurities present in the natural vermiculite should be removed.

The lubricant composition is prepared by acareful stirring of the components in a mechanical mixer for 45 minutes in the temperature range from about 60 C.

to about 80 C. The lubricant components are taken in the above-mentioned amounts.

While processing the pressing operation, the mentioned lubricant composition is applied in a commonly known way, i.e. it is applied to the upper end of a skelp in the than with the use of a graphite-oil lubricant. Yet, in the I process of pressing tubes having the wall thickness less 3 1 than 3.5 mm., the peak pressing force is higher by -15 percent than in the case of the pressing with the useof a lubricant composition containing the same amount of graphite instead of vermiculite. This disadvantage is eliminated when the lubricant composition contains up to 16 weight percent of graphite. Such an amount of graphite in combination with a predominant amount of vermiculite provides only a minor improvement in the carbonizing characteristics of the lubricant composition and this practically shows no effect on the quality of articles.

For a better understanding of the present invention, the following examples of the lubricant composition for use in the hot pressing of metals and the method of the preparation thereof are presented by way of illustration:

EXAMPLE 1 The lubricant composition taken in weight percent: Vermiculite 40 Flaky graphite 16 Cylinder oil (flash point3l0 C., kinematic viseosity-44 to 59) 27 Wood saw-dust 9 Sodium chloride 8 The given lubricant composition was prepared as follows:

- An amount of vermiculite free of mechanical impurities was heated at a temperature of about 900 C. to about 1100 C., for 10 minutes, then it was ground and screened. The particle size of vermiculite was less than 0.6-1 mm. The screened vermiculite in an amount of 40 kgs. was charged into a mechanical mixer, then 16 kgs. of flaky graphite, 9 kgs. of wood saw-dust, 8 kgs. of sodium chloride, and 27 kgs. of cylinder oil were added.

The components were carefully stirred up for 45 minutes at a temperature of about 60C. to about 80 C. to obtain a final product.

The obtained lubricant composition was tested in comparison with a graphite-oil lubricant of the following composition taken in weight percent:

Graphite 56 Cylinder oil (flash point--3l0 C., kinematic viscosity-44 to 59) 25 Wood saw-dust 11 Sodium chloride 8 The test was conducted in the process of producing boiler tubes of low-alloy steel 57 x 8 mm. in size. The skelps were heated up to a temperature of about 1180- 1190 C. The container was 160 mm. in diameter. The surface quality of the produced tubes complied with the design requirements. The force necessary for the tube pressing with the use ofthe advanced lubricant composition was 910/640 tons and with the use of the known graphite-oil lubricant it was 940/670 tons. The tubes pressed with the use of the advanced lubricant composition were free of carbonization, while the surfaces of the tubes pressed with the use of the graphite-oil lubricant were carbonized up to a depth of 0.3 mm.

With the use of the advanced lubricant composition and the known graphite-oil lubricant, the medium endurance of matrix rings came to 52 and 43 pressings, re-

4 EXAMPLE 2 described in Example 1. The skelps were heated ,up to a temperature of about l-1230 C. The surface quality of the produced tubes, the endurance of tools: and :the pressing force were similar for both lubricants. The depth of the carbonization layer on the tube surfaces with the use of the advanced lubricant did not exceed 0.1 mm. as it was noted only on two tubes while, with the use of the graphite-oil lubricant, it was about 0.4 mm. The subsequent cold rolling oi the tubes satisfied the design requirements.

EXAMPLE 3 The lubricant composition and the method of the preparation thereof were similar to those described in Example 1.

The test was conducted in the process of producing boring tubes of manganese-silicon steel 50 x 5.5 mm. 111 size with the use of the lubricant compositions similarto those used in Example 1. The skelps were heated up to a temperature of about l210-l220 C.

The surface carbonization of the tubes with the use of the advanced lubricant was not noticed while, with the use of the graphite-oil lubricant, the pressed tubes were rejected because of a high carbonization corresponding to lebedurite.

This lubricant composition was prepared similarly to that described in Example 1.

The obtained lubricant composition was tested in comparison with the graphite-oil lubricant as it is describedin Example 1.

The test was conducted in the process of producing tubes of low-carbon steel 57 x 7.5 mm. in size.

The skelps were heated up to a temperature of about 1170-1180 C. The container was mm. in diameter. The surface quality of the produced tubes and the tool endurance satisfied the design requirements. The pressing force with the use of the advanced lubricant was 1100/ 750 tons while, with the use of the graphite-oil lubricant, it was equal to 1090/785 tons. I

With the use of the advanced lubricant composition, no carbonization was noticed at all white, with the use of the graphite-oil lubricant, the tube surfaces were carbonized up to a depth of 0.35 mm.

EXAMPLE 5 The lubricant composition and the method of the preparation thereof were similar to those described in Example 4. The test was conducted in" the process of producing tubes of low-carbon steel 42 x 30 mm. in size with theme of the lubricant composition described in" the use of the graphite-oil lubricant, the tube surfaces were carbonized up to a depth of 0.38 mm. The pressing force with the use of the advanced lubricant was 1450/ 1000 tons while, with the use of the graphite-oil lublim it was equal to 1300/ 950 tons.

Vermiculite 60-38 Graphite Ol 6 Mineral oil 33-23 Wood saw-dust 3-11 Sodium chloride 4-12 2. A lubricant composition according to claim 1 which comprises the following components taken in weight percent:

vermiculite 56 Flaky graphite Mineral oil 29 Wood saw-dust 8 Sodium chloride 7 3. A lubricant composition according to claim 1 which comprises the following components taken in weight percent:

Vermiculite 4O Flaky graphite 16 Mineral oil 27 Wood saw-dust 9 Sodium chloride 8 4. A method for the preparation of a lubricant composition of improved quality and capable of reducing the surface carbonization of pressed materials and elimination of special thermal treatment for decarbonizing pressed articles made from said pressed material and according to claim 1 comprising the steps of heating vermiculite free of mechanical impurities up to a temperature of about 900-l100 C., subsequently grinding said vermiculite and mixing it with graphite, wood sawdust, sodium chloride and a mineral oil at a temperature in'a range of from about C. to about C. to obtain a final product.

5. The method according to claim 4, wherein the vermiculite is ground to a particle size less than 0.6-1 mm.

References Cited UNITED STATES PATENTS 2,791,674 5/1957 Westin et al. 252-30 2,757,138 7/1956 Clatot et a1. 25230 2,968,617 1/1961 Reykjalin 252-30 DANIEL E. WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner US. Cl. X.R. 

